The present invention is directed to synergistic, anxiolytic combinations of one of 8-hydroxy-2-(dipropylamino)tetralin, gepirone, ipsapirone, tandospirone, (7S,9S)-2-(2-pyrimidyl)-7-(succinimidomethyl)perhydro-1H-pyrido[1,2-a]pyra zine, or chlordiazepoxide; with either 1-(2-pyrimidyl)pyrazine or idazoxan.
It is well established that Vogel's so-called anticonflict test or drinking conflict test is a specific and reliable model for the detection of drugs having anxiolytic activity (for example, see Soderpalm et al., J. Neural Transm., v. 16, pp. 191-204, 1989, at page 192) Compounds which have been reported to possess activity in this test include said 8-hydroxy-2-(dipropylamino)tetralin (Engel et al., European J. Pharmacol., v. 105, pp. 365-368, 1984; no significant activity noted under the conditions used in present studies); gepirone, having the formula ##STR1## (Temple Jr., U.S. Pat. No. 4,423,049; activity confirmed in present studies); ipsapirone, having the formula ##STR2## (Dompert et al., German patent publication 3,321,969-Al; activity confirmed in present studies); tandospirone, having the formula ##STR3## (Ishizumi et al., U.S. Pat. No. 4,507,303; also known as SM-3997; activity confirmed in present studies); (7S,9S)-2-(2-pyrimidyl)-7-(succinimidomethyl)perhydro-1H-pyrido[1,2-a]pyra zine (Bright et al., published International Patent Application No. WO 90/08147; also known as CP-93,393; activity confirmed in present studies); chlordiazepoxide (Soderpalm et al., cited above; activity confirmed in present studies; idazoxan (racemic-2-(1,4-benzodioxan-2-yl)-2-imidazoline; Gower et al., European J. Pharmacol., v. 155, pp. 129-137, 1988; activity confirmed in present studies); and 1-(2-pyrimidyl)pyrazine (Gower et al., loc. cit.; activity confirmed in present studies).
Gower et al., loc. cit., have reported buspirone (an anxiolytic agent structurally related to above gepirone, ipsapirone and tandospirone) in combination with idazoxan shows a simple additive effect in the Vogel anticonflict test. Soderpalm et al., loc. cit., have reported that, after coadministration of idazoxam, rats treated with alprazolam or diazepam (benzodiazepines structurally related to present chlordiazepoxide) accepted significantly more shocks in the Vogel anticonflict test.